The present invention relates generally to atomic and molecular modeling, and more particularly, to methods and systems for teaching and demonstrating atomic and molecular models.
Chemistry is typically taught through examination and explanation of common, rudimentary atomic and molecular structures. By way of example, individual atoms such as a silicon atom, and common molecules such as a water molecule, H2O and an oxygen molecule O2 are often examined.
FIG. 1A is a typical model of a silicon atom 100. The model of the silicon atom 100 illustrates the valence shells 102, 104 of the electrons in the silicon atom. The silicon atom 100 includes twelve electrons shown as small dark circles. The twelve electrons are distributed over the two valence shells 102 and 104. The lower valence shell 102 is filled with eight of the electrons and the higher or outermost valence shell 104 includes four electrons 108.
Each of the atom's valence shells 102, 104 have an affinity for being filled. For many elements (e.g., carbon, oxygen and nitrogen) a filled valence shell contains eight electrons. This is referred to as the “octet” rule. By way of example, the outermost valence shell 104 of the silicon atom 100 has only four electrons rather than a full complement of eight. As a result, the outermost valence shell 104 has an affinity for four additional atoms that can be gained by bonding with other atoms in a covalent bond. Representing an atom with the available valence electrons shown is often referred to as a dot-model of the atom. The dot model can be used to predict that atoms will share valence electrons (with shared electrons “counting” for both atoms) until the atoms have filled their valence shells and therefore can be used to predict which elements will combine to form molecules. By way of example, the silicon atom 100 will want to form covalent bonds with one or more atoms that have a total of four valence electrons available to share with the silicon atom.
Covalent bonding is a chemical theory that states that atoms bond together to form molecules by sharing pairs of electrons. Single bonds involve sharing one pair of valence electrons, double bonds involve sharing two pairs of valence electrons and triple bonds involve sharing three pairs of valence electron. The oxygen molecule and the water molecule can be used to exemplify the concept of covalent bonding.
FIGS. 1B and 1C illustrate typical chemical equations for an oxygen molecule 120 and a water molecule 130, respectively. Referring to FIG. 1B, two oxygen atoms combine to form an oxygen molecule (O2) in a chemical reaction 120. Chemical equation 122 shows the two oxygen atoms and the oxygen molecule 124 in a dot model form showing that each of the oxygen atoms has six valence electrons in its outer valence shell. The oxygen molecule 124 shows that the two pairs of valence electrons 126A and 126B are shared by the two oxygen atoms to provide each of the oxygen atoms with eight electrons in the outermost valence shell.
Referring to FIG. 1C, two hydrogen atoms and an oxygen atom combine to form a molecule of water. Chemical reaction 132 shows the two hydrogen atoms and the oxygen atom combining to form the water molecule 134 in a dot model form. Each of the hydrogen atoms has a single valence electron and the oxygen atom has six valence electrons in its outer valence shell. The water molecule 134 shows that the each one of two pairs of valence electrons 136A and 136B are shared by one of the hydrogen atoms and the oxygen atom to provide the oxygen atom with eight electrons in the outermost valence shell. The covalent bonding also provides each of the hydrogen molecules with a valence shell having two valence electrons.
This manual dot-model is useful in teaching or explaining the basics of chemistry however, because the dot-models are manually formed, many mistakes can occur and can make it more difficult and time consuming as a learning tool. In view of the foregoing, there is a need for a simpler and easier to use and understand system and method for teaching covalent bonding.